Horizon and its allies continued to attack the proposal Tuesday, saying it amounted to a state takeover of a private company. Horizon says that setting aside “excess” surplus for the general public would force premium hikes on its 3.8 million policyholders.

The conservative group Judicial Watch — which successfully sued the State Department for access to emails regarding the Clinton Foundation — joined the fray, calling Christie’s proposal extortion. The group said it had filed a public-records request in New Jersey seeking correspondence regarding Horizon among Christie; George E. Norcross III, chair of Cooper University Health Care’s board; and Cooper executive Kevin O’Dowd.